Toshiba e-STUDIO520 Service Manual page 414

7) EEPROM circuit
This circuit is an EEPROM to store RADF data and its peripheral circuit.
IC3 is a memory to store the adjustment value for reflection-type sensors, and data are sent/
received between IC3 and CPU using a 4-line type serial interface. Data saved in the IC3 is not
erased even if the power is turned OFF.
IC3-1 pin (CS) is a chip selection terminal and its level is "H" when data are being sent/received.
IC3-2 pin (SK) is a serial clock terminal, and the serial data are sent in synchronization with the clock
input which is input to this terminal.
IC3-3 pin (DI) is a input terminal for serial data and IC3-4 pin (DO) is an output terminal for serial
data.
8) Conversion circuit for D-A
This is a circuit of the D-A converter to converse the digital signal from CPU to the analog signal.
Controls of CPU are done by the serial communications of each DI, CLK, LD signal. The analog out-
put signals from Ao1 to Ao4 are used to adjust the light intensity of the light emitting diode (LED) of
the reflective sensor. Also, Ao5 and Ao6 output 5 V or 0 V and are used as the output ports.
e-STUDIO520/600/720/850 REVERSING AUTOMATIC DOCUMENT FEEDER (RADF)
Fig.16-100
Fig.16-101
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March 2005 © TOSHIBA TEC